Welding Fume Hazards: A Closer Look at Galvanized Steel

Welding, a critical process across countless industries, is as much an art as a science. It is a craft that has shaped our world, from the tallest skyscrapers to the cars we drive. Among the numerous materials manipulated by this trade, galvanized steel stands out due to its unique properties and widespread usage (automotive, energy, construction, telecommunications, etc.).

This steel variant, treated with a protective layer of zinc to prevent rusting, is often chosen for its durability and resilience. However, the very process that makes it so desirable also presents specific challenges, particularly during welding.

In this blog post, we’ll delve deep into galvanized steel, focusing on the hazards associated with welding fume and, importantly, ways to mitigate these risks. Understanding these risks is essential for welders and those who work near the welding process.

As we navigate this topic, we hope to shed light on the safety measures to make this vital industrial operation safer for all involved.

Understanding Galvanized Steel

Galvanized steel, a widely used material in numerous industries, is steel that has been treated through a process known as galvanization. Galvanization involves coating the steel with a layer of zinc. The most common method is hot-dip galvanizing (parts are submerged in a zinc bath). The galvanizing process has existed for more than 250 years and has been a mainstay of North American industry since the 1890s.

Zinc is a vital metal, silvery-white in color, and naturally found in the Earth’s crust. But why zinc, you may wonder? The answer lies in zinc’s ability to corrode at a significantly slower pace compared to steel. This means that even if the zinc layer suffers some damage, the steel underneath remains protected from rust for a considerable time.

The decision to galvanize steel is largely based on its intended application. Due to its rust-resistant properties, galvanized steel is a prime candidate for outdoor constructions, such as bridges, fences, and railways. It’s also frequently used in the automotive industry and for manufacturing home appliances.

However, the aspect that makes galvanized steel advantageous – its protective zinc coating – becomes a point of concern during welding. At this juncture, the question of fume hazards comes into the spotlight. In the following sections, we will explore these hazards in more depth, examining the welding process for galvanized steel and its potential risks.

The Welding Process of Galvanized Steel

Welding galvanized steel isn’t vastly different from welding any other type of steel, but it does involve a few critical nuances due to the presence of the protective zinc coating. This zinc layer can react with heat differently than bare steel, and it’s during this reaction that potential hazards can arise.

In welding, intense heat is applied to the metal, causing it to melt and allowing the welder to manipulate and fuse the material. When welding galvanized steel, the heat affects the steel itself and the zinc coating. As the temperature rises, the zinc vaporizes and reacts with the surrounding oxygen to create zinc oxide. This reaction results in the formation of fumes.

Galvanized steel fumes, though invisible to the naked eye, are a significant concern in the welding industry. They contain particulates of zinc oxide, a compound that can have detrimental health effects if inhaled in large quantities or over a prolonged period. They can also contain lead oxide, which is toxic as well.

The severity of the fume generation largely depends on the welding technique used, the heat applied, and the thickness of the zinc coating.

Air sampling is usually necessary to know the exact composition of the welding fume in your work environment. Although zinc oxide and lead oxide are obvious and concerning issues, other substances might also be dangerous.

Recognizing these risks is crucial for welders and those responsible for maintaining safe and healthy work environments.

Health Hazards Associated with Welding Galvanized Steel

Welding galvanized steel poses several health risks that stem primarily from inhaling the toxic zinc oxide fumes generated during the process. Exposure to these fumes can result in both immediate and long-term health issues.

One of the most common immediate health problems when welding galvanized steel is a condition known as ‘metal fume fever,’ probably the best-known occupational disease amongst welders. Hundreds of documented cases of metal fume fever occur annually in the USA only.

This is especially true in this case, as zinc oxide inhalation is one of the most important causes when it comes to metal fume fever (source: National Library of Medicine).

Metal fume fever is an illness like the flu, with symptoms often including chills, fever, nausea, and body aches. These symptoms typically arise four to ten hours after exposure.

As reported by pubmed.gov, metal fume fever, or galvanize poisoning, is typically a benign disease with spontaneous resolution of symptoms after 12 to 48 hours following cessation of exposure. But it does have the potential to be serious, especially for workers with pre-existing medical conditions.

Although usually temporary and reversible, experiencing metal fume fever is a sign that fume exposure is too high and should be promptly addressed.

Chronic exposure to zinc oxide fumes when welding galvanized steel can have severe consequences in the long term. These may include lung damage, leading to conditions such as pneumonitis and pulmonary edema.

Additionally, zinc competes with the absorption of copper in the body, and overexposure to zinc can lead to a copper deficiency, causing neurological issues.

As mentioned earlier, when welding galvanized steel, fumes also contain lead oxide, which can cause long-term health problems such as lung and brain cancer and even complications in the nervous system.

In general, according to OSHA, the CDC, the IARC, and the CNESST, breathing welding fumes could also cause the following health effects:

• Eye, nose, and throat irritation
• Dizziness and nausea
• Breathing difficulties that could lead to suffocation or asphyxiation
• Lung damage and various types of cancer
• Stomach ulcers
• Kidney damage
• Nervous system damage
• Manganism
• Chest pain
• Asthma
• Bleedings
• Dermatitis or eczema
• Kidney disease
• Bone and joint disorders
• Siderosis (iron oxide in lung tissue after inhalation)
• Stannosis (tin oxide in lung tissue after inhalation)
• Anthracosis (poisoning after inhalation of carbon dust)
• Berylliosis (poisoning after inhalation of beryllium dust)
• Accumulation of fluid in the lungs

It’s important to note that individual sensitivity to these fumes can vary greatly. While some welders might develop symptoms after minimal exposure, others might not experience any symptoms despite consistent exposure. However, this doesn’t mean the latter group is immune or less at risk. It underscores the need for all workers to adhere to safety guidelines to protect their health.

Understanding these health risks is paramount for welders and those involved in work environments where the welding of galvanized steel occurs. This knowledge keeps workers safe and helps organizations adhere to safety regulations, which we will discuss in the next section.

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Regulatory Guidelines on Welding Fumes

To ensure the safety of workers, several regulatory bodies have established guidelines related to welding fumes. These organizations include OSHA in the United States and different provincial agencies in Canada, and they exist to protect workers from the potential hazards associated with their profession.

Abbreviations used in the tables:

• TWA: Time-Weighted Average for 8 hours
• STEL: Short-Term Exposure Limit (maximum for 15 minutes)
• C: Ceiling (must never be exceeded)
• (i): Inhalable particles
• (r): Respirable particles
• ALARA: As Low as Reasonably Achievable

Galvanized steel welding fume regulations in the US

OSHA PEL	TWA	STEL	C
Welding Fumes	5mg/m3(r)	None	None
Zinc Oxide	5mg/m3(r)	None	None

To know more about the maximum concentrations allowed for other substances, you can read the following article: Welding Fume Regulations and Exposure Limits in the US.

Galvanized steel welding fume regulations in Canada

Welding Fumes	TWA	STEL	C
Alberta	ALARA	ALARA	ALARA
British Columbia	10mg/m3 (i) 3mg/m3 (r)	30mg/m3 9mg/m3	50mg/m3 15mg/m3
Manitoba	10mg/m3 (i) 3mg/m3 (r)	None	None
New Brunswick	10mg/m3 (i) 3mg/m3 (r)	None	None
Newfoundland and Labrador	10mg/m3 (i) 3mg/m3 (r)	30 mg/m3 9 mg/m3	50 mg/m3 15 mg/m3
Northwest Territories	5mg/m3	10 mg/m3	None
Nova Scotia	10mg/m3 (i) 3mg/m3 (r)	None	None
Nunavut	5mg/m3	10mg/m3	None
Ontario	10mg/m3 (i) 3mg/m3 (r)	30mg/m3 9mg/m3	50mg/m3 15mg/m3
Prince Edward Island	10mg/m3 (i) 3mg/m3 (r)	None	None
Quebec	5mg/m3	15mg/m3	25mg/m3
Saskatchewan	5mg/m3	10mg/m3	None
Yukon	5mg/m3	5mg/m3	None

Zinc Oxide	TWA	STEL	C
Alberta	2mg/m3	10mg/m3	None
Yukon	5mg/m3(r)	10mg/m3(r)	None
Other Provinces & Territories	2mg/m3(r)	10mg/m3(r)	None

To know more about the maximum concentrations allowed for other substances, you can read the following article: Welding Fume Regulations and Exposure Limits in Canada.

Workplaces must abide by these guidelines to ensure worker safety. Non-compliance can lead to penalties, including hefty fines and potential lawsuits. Moreover, neglecting these regulations can lead to serious health consequences for employees, impacting their overall well-being and productivity.

Mitigating Risks: Effective Fume Extraction and Safety Practices

Mitigating the risks associated with welding galvanized steel primarily involves proper fume management and implementing effective safety measures. It’s about creating an environment that prioritizes health and safety without compromising on the efficiency of the work process.

We have developed an 8-step method to address welding fume problems. Here are a few ideas that apply directly to galvanized steel fume. It would be best to read this article afterward to understand the whole process.

Step 4: Use consumables and materials that produce less toxic fume

It is typically a good idea to complete welding before galvanizing the steel.

Otherwise, according to the American Welding Society, galvanized metal must be cleaned using a grinder or other abrasive means to remove the galvanized coating at least 1-4 inches from either side of the intended weld and on both sides of the workpiece before welding.

It reduces toxic fumes, probably even producing lead and zin oxide emissions below the PELs. But it will also improve the weld quality as the coating makes the penetration more difficult and could cause porosity. The protective layer must be restored after welding, whether removed before or not.

High-performance fume extractors become even more critical if you decide to weld coated steel. You will likely need to select a filler material made for zinc-coated materials. And the process will need a higher heat input to remove the zinc from the weld pool and lower welding speeds to burn off as much of the zinc coating ahead of the weld

Finally, zinc electroplated steel has a thinner and more uniform coat of zinc than hot dipped or zinc thermal sprayed steel (which also makes it more appropriate for automatic welding).

Step 5: Use welding fume extractors

The best way to manage fumes is through an efficient extraction system. Welding fume extractors are designed to capture and filter out the harmful fumes produced during welding, ensuring they do not linger in the workspace and are not inhaled by workers.

A fume extraction gun is the most efficient way to extract galvanized welding fume for MIG welding. For TIG welding, we recommend using a fume extraction arm.

Drinking milk is useless

It is important to note that the idea that drinking milk can prevent the harmful effects of welding fumes is one of the many welding myths. The origin of this misconception is unclear, but it is likely based on the idea that calcium in milk can bind with heavy metals and help to eliminate them from the body. However, no scientific evidence supports this claim, and it is a dangerous idea that can lead to a false sense of security.

Conclusion

The welding of galvanized steel, while essential to numerous industries, presents a series of health hazards that cannot be overlooked. The production of zinc oxide fumes during welding can lead to immediate ailments, such as metal fume fever, and pose long-term health risks with chronic exposure. However, understanding these hazards is the first step in mitigating them.

We can substantially reduce these risks through effective safety measures, like utilizing efficient fume extraction systems and following best practices in welding. Compliance with regulatory guidelines ensures the safety of individual workers but also the overall health of the workplace environment.

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